This invention relates to fiber optic (optoelectronic) communications, and more particularly to pluggable fiber optic transceivers utilized in fiber optic systems.
Fiber optic transceivers facilitate bi-directional data transmissions between electronic devices (e.g., computer, input/output system, peripheral device, or switch) and optical data links in fiber optic (optoelectronic) systems. Each transceiver includes a photodetector for converting optically encoded data received from an optical data link to electrically encoded data readable by a host electronic device, and a laser diode for converting electrically encoded data signals from the host electronic device that are converted into optical signals and transmitted to the optical data link. Each transceiver is mounted onto a circuit card assembly of the host electronic device, and is therefore typically packaged such that it occupies as little circuit card surface area as possible.
Small Form-factor Pluggable (SFP) transceivers are one type of transceiver having standardized physical dimensions and performance characteristics that are defined in the xe2x80x9cCooperation Agreement for Small Form-Factor Pluggable Transceiversxe2x80x9d, as executed on Sep. 14, 2000 (herein xe2x80x9cthe Cooperation Agreementxe2x80x9d), which is incorporated herein in its entirety. The Cooperation Agreement is part of an SFP Transceiver multi-source agreement whose purpose is to establish internationally compatible sources of pluggable fiber optic transceivers in support of established standards for fiber optic systems. Specifically, the Cooperation Agreement sets forth transceiver package dimensions, cage and electrical connector specifications, host circuit board layouts, electrical interface specifications, and front panel bezel requirements that are followed by each party.
FIG. 1 is a simplified exploded perspective view depicting a transceiver assembly 100 that complies with the Cooperation Agreement. Transceiver assembly 100 includes a host circuit board 130 upon which is mounted a standard female electrical connector 140, a pluggable transceiver 150, a cage 160, and an optional bezel 180 (shown in dashed lines) that is mounted over the front end of transceiver assembly 100.
Pluggable transceiver 150 includes transceiver electronics that are mounted in an elongated transceiver housing 151 that is designed for xe2x80x9cpluggablexe2x80x9d insertion into cage 160. Transceiver housing 151 includes an upper surface defining several vent holes, a lower surface including a boss 152 (shown in dashed lines), and a front surface defining pair of receptacles 153 for receiving standard optical connectors 190 (e.g., duplex LC, MT-RJ, or SC connectors). Mounted within housing 151 is a circuit board 154 for supporting the transceiver electronics, which process data signals from and supply data signals to a photodetector 155 and a laser diode 156, respectively. A pair of ferrules 157 is mounted in receptacles for aligning standard optical connectors (not shown) with photodetector 155 and laser diode 156. Extending from the back end of circuit board 154 is a male connector card 158 including contacts 159 that mate with corresponding contacts 144 of female connector 140 when cage 160 is mounted on host circuit board 130 and pluggable transceiver 150 is fully inserted into cage 160.
Referring to the center of FIG. 1, cage 160 includes a first side wall 161, a second side wall 162, a top wall 163, and a bottom wall 164 that collectively define a front opening 165 for receiving pluggable transceiver 150. Cage 160 also includes a back wall 166, which includes a leaf spring for biasing transceiver 150 toward opening 165. Extending downward from side walls 161 and 162 and back wall 166 are feet 167 that are press fitted into holes 135 formed in host circuit board 130. Note that holes 135 are plated with a conductive material 136 to provide a ground connection between cage 160 and host circuit board 130. Bottom wall 164 and back wall 166 define an opening for receiving female connector 140 when cage 160 is press fitted onto host circuit board 130. A series of resilient clips 168 are formed by folding elongated tabs extending from walls 161, 162, 163, and 164, and are utilized to provide electrical connection between cage 160 and optional bezel 180. Formed on bottom wall 164 of cage 160 is a transceiver latch 170 that defines a latch opening 175 for receiving boss 152 provided on the lower surface of transceiver housing 151 to secure transceiver 150 inside cage 100. A series of vent holes are formed on top wall 163 that align with vent holes formed in transceiver housing 151 (discussed above), and cooperate with an optional system ventilation (cooling) system to maintain transceiver 150 at a desired operating temperature. Cage 160 includes dimensions that are consistent with the standards set forth in the Cooperation Agreement, and is discussed in further detail in co-pending U.S. Patent application Ser. No. 09/810,820-6776, entitled xe2x80x9cSINGLE-PIECE CAGE FOR PLUGGABLE FIBER OPTIC TRANSCEIVERxe2x80x9d, which is incorporated herein by reference.
FIGS. 2(A) through 2(D) are simplified partial side views depicting the attachment and subsequent removal of transceiver 150 to/from cage 160. As indicated in FIGS. 2(A), 2(B) and 2(C), as transceiver 150 is pushed into cage 160 (i.e., between upper wall 163 and lower wall 164 in the direction indicated by arrow A), transceiver latch 170 is pushed downward (i.e., bent away from transceiver housing 151 in the direction indicated by arrow B) by boss 152 until boss 152 enters latch opening 175, at which point transceiver latch 170 is resiliently biased upward (i.e., in the direction indicated by arrow C; see FIG. 2(C)). In this latched state, movement of transceiver 150 out of cage 100 (i.e., in the direction of arrow D in FIG. 2(C)) is prevented by the contact between boss 152 and the inner edge of latch opening 175. As shown in FIG. 2(D), subsequent manipulation of latch 170 (e.g., by a manual force F) releases boss 152 from latch opening 175, thereby allowing removal of transceiver 150. Ideally, the spring provided on back wall 166 of cage 160 pushes transceiver 150 forward (i.e., in the direction of arrow D) when latch 170 is manipulated as shown in FIG. 2(D).
A problem associated with the conventional transceiver latching mechanism depicted in FIGS. 2(A) through 2(D) is that in highly populated arrangements (i.e., in which many transceiver assemblies are mounted in close proximity), it is often very difficult to manipulate transceiver latch 170, thereby making it difficult to remove transceiver 150 from cage 160.
FIG. 3 is a simplified side view showing a xe2x80x9cbelly-to-bellyxe2x80x9d configuration in which two transceiver assemblies 100-1 and 100-2 are mounted on opposite sides of host circuit board 130. Specifically, a first cage 160-1 is mounted on an upper side of host circuit board 130 into which a first transceiver 150-1 is inserted, and a second cage 160-2 is mounted on a lower side of host circuit board 130 into which a second transceiver 150-2 is inserted. Such a xe2x80x9cbelly-to-bellyxe2x80x9d arrangement is utilized to facilitate highly populated circuit boards that minimize space requirements. A problem with this and other highly populated transceiver arrangements is that they make accessing and manipulating transceiver latches (e.g., transceiver latches 170-1 and 170-2; see FIG. 3) very difficult, thereby increasing maintenance costs. Further, manipulation of conventional transceiver latches is not reliable and confusing.
What is needed is a release mechanism for pluggable fiber optic transceivers that is easy to access in highly populated transceiver arrangements, and is both reliable and intuitive.
The present invention is directed to a release mechanism for pluggable fiber optic transceivers including an intuitive, reliable and easily manipulated key-like locking member that is easily accessed for locking, unlocking, and removing a host transceivers from an associated transceiver cage.
In accordance with a first embodiment, the locking member includes a lever that extends from a front end of the transceiver housing. When the transceiver is unlocked, the lever is in a vertical position that blocks the transceiver receptacles, thereby intuitively notifying a user of the unlocked condition by blocking the insertion of fiber optic connectors. Conversely, when the transceiver is locked, the lever is rotated into a horizontal position and below the transceiver receptacles, thereby allowing insertion of a fiber optic connector. Accordingly, the lever intuitively notifies a user when a transceiver is locked and unlocked. Further, because the lever is actuated like a key, a user intuitively pulls on the lever when the lever is in the unlocked position, thereby facilitating a convenient and intuitive mechanism for removing transceivers from associated cages. Moreover, the levers are do not interfere with each other in belly-to-belly highly populated transceiver assemblies by rotating in opposite directions.
In accordance with an aspect of the present invention, the release mechanism includes a cam positioned in a recess formed in a bottom wall of the transceiver housing adjacent to the latch boss. When the lever is rotated into the unlocked position, the cam extends out of the recess and pushes the transceiver latch of a host cage away from the boss, thereby reliably facilitating removal of the transceiver. Conversely, when the lever is rotated into the locked position, the cam is rotated into the recess, thereby allowing the transceiver latch to move toward the bottom wall of the transceiver housing such that the boss engages the latch opening formed in the transceiver latch to reliably secure the transceiver in the cage.
In accordance with yet another aspect of the present invention, the locking member further includes a shaft that is rotatably coupled to the transceiver housing to transmit torsion from the lever to the cam. In one embodiment, the release mechanism includes a snap-coupling structure provided on the bottom wall of the transceiver housing for receiving the shaft to facilitate low cost assembly. In addition, the shaft includes one or more self-alignment rings that maintain the release mechanism in a proper position on the transceiver housing.